Run script stored in text editor/blend file from CLI
Run blender --help and look for any option with 'Python' in the name. You'll find that it's blender filename.blend --python-text Import.

Alternatively, name your script yourscript.py (so end it in .py), and you can enable the "Register" checkbox to automatically run the script whenever you load the blend file. This can be easier, depending on your needs.